When you search through auction catalogues that are from auctions that are entirely devoted to exotic and rare antique frames, you will inevitably come across frames described as being à décor Bérain Epoque Louis XIV. These frames preceded the Louis XV frames and are easily distinguished from them, particularly in the cross section profiles. I show this below in Comparative Diagram 1, I have borrowed the "typical profiles" from William B. Adair's excellent paper entitled Ornamentation in Frame Design that you can download in pdf format here.

In Comparative Diagram 1, I have elected to show frame examples which may not be typical but at least I am certain that they are representative. The Louis XIV example comes from a 2008 Auction catalogue
CADRES EXCEPTIONNELS DE LA COLLECTION GEORGES BAC, BAGUETTES A DESSIN ET CADRES ANCIENS ET MODERNES Italiens, français, espagnols, hollandais et d'Europe du Nord des XVIIe, XVIIIe, XIXe et XXe siècles. published by La société EVE. This is the frame they illustrate as Lot 154, one of the most expensive frames in the catalogue at an estimated price of 20 to 25,000 Euros, we can be reasonably sure that it is what they claim:

Unfortunately I have not yet found a high resolution image of it, if anyone has a better image of this frame please share it with us. The Louis XV frame is found on a painting in a Sotheby's 2012 catalogue Important Old Master Paintings and Sculpture, New York, Lot 62, which has been expertly described in the lot description:

"The frame which accompanies this painting represents the epitome of a grand-luxe portrait frame in late Louis XV style, and the finest of its pattern recorded by Paul Mitchell and Lynn Roberts. A group of earlier frames on Nattier's portraits of the 1740s are identical to each other, indicating that he, like many artists, was generally faithful to one workshop of carvers and gilders.1 This workshop would have been part of the Bâtiments du roi, run by one of the dynasties of families who acted as framemakers and carvers of boiseries to the French court: for instance Mathieu Legoupil, whose sketches in his carnets show details highly reminiscent of this frame, in the frieze panels, and in the lush foliation of the rails."

Lot 62.
was a 1756 painting by JEAN-MARC NATTIER, a
PORTRAIT OF JEAN VICTOR DE ROCHECHOUART, DUC DE MORTEMART, IN THE CEREMONIAL DRESS OF A COLONEL OF THE ORDER OF SAINT LOUIS. Pre auction estimates were between 500,000 - 700,000 USD, while the lot sold for 602,500 USD (Hammer Price with Buyer's Premium.)
Thus I think we can rest assured of the frame's authenticity and provenance. If you are just starting out on the hunt for these frames I just want to mention an easy way to recognize the difference between the Louis XIV and the Louis XV, it is really quite simple. Because of the particular characteristics of the Louis XV frames, you are able to see both the front and the back (so called) at the same time, (looking directly at the frame while standing immediately in front of it). Some might say "front and side", but either way it is quite different from most frames in this respect. If you look closely at the Louis XIV frame pictured at the top of this page you will see that you can just see part of the side or "back" of the frame because the picture was taken at a slight angle... this then is the big difference in these two styles.

I wanted to point out the differences in the frames, because we are now going to return to our subject of research, which is the alternating Acanthus frieze around the inside border or sight edge of these frames. Most of the Louis XIV frames à décor Bérain
will have been made before 1715. The example shown below on the Laurent de La Hyre 1647 painting Laban cherchant ses idoles dans les bagages de Jacob was not made in 1647, but is anyway much older than all the Louis XV frames and yet bears an identical alternating Acathanus frieze pattern along the sight edge.